Interleukin-8 (hereinafter referred to as IL-8) is a cytokine induced by monocytes, macrophages, fibroblasts, vascular endothelial cells, skin keratinized cells, renal mesangial cells, epithelial cells of intestine and respiratory tract, liver parenchyma cells and various tumor cells, and is known as a potent chemotactic factor affecting neutrophil, T-lymphocyte and basophil.
IL-8 has been reported to effectively influence the maturity of the uterine cervix in delivery and interrupted pregnancy (see WO93/09796), to have a therapeutic effect on allergic disease causing asthma, etc. by inhibiting histamine--releasing factor (HRF) from basophils (see WO92/01465), to have a therapeutic effect on Alzheimer disease and Huntington disease etc. by protective effects on the neuronal cell (see Chemical Abstracts Vol.119: 109015k), to be effective as an accelerating agent for healing wounds such as skin burns by accelerating the increase in vascular endothelial cell (see Chemical Abstracts Vol.119: 201760k) and so on. Furthermore, IL-8 is expected to develop an agent to target improvement of immunodeficiency, prevent opportunistic infection, promote anti-tumor effect, etc. by activating neutrophils and enhancing anti-bacterial effects [Zoketsu Inshi (Hematopoietic Factor), Vol.2, No.1, 46, 1991 and Med. Immunol., Vol.20, No.3, 305, 1990].
Dehydroepiandrosterone sulfate (hereinafter referred to as DHAS) or a pharmaceutically acceptable salt thereof improve the maturity of the uterine cervix and the sensitivity of uterine musculature to oxytocin in the late phase of pregnancy (see U.S. Pat. No. 4,005,200). The sodium salt performed well as an agent to improve the maturity of the uterine cervix. It is also well known that DHAS or a pharmaceutically acceptable salt thereof are effective as therapy for dementia (see U.S. Pat. No. 4,868,161), therapy and prevention of hyperlipemia (see GB2208473), therapy for osteoporosis (see U.S. Pat. No. 5,116,828) and therapy for ulcer (see Chemical Abstracts Vol. 122 142528q).
Furthermore, DHAS or a pharmaceutically acceptable salt thereof have been reported to increase the production of interleukin-2 and interleukin-4 (see WO91/04030), normalize the level of interleukin-6 induced abnormally by injury, aging and autoimmune disease (see WO93/21771).
However, neither DHAS or a pharmaceutically acceptable salt thereof has been reported to increase the effect of IL-8.